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Патент USA US3052141

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Sept. 4, 1962
o. DlTTRlCH ET AL
3,052,132
CONTROL MECHANISM FOR INFINITELY VARIABLE GEARS
Filed Dec. 10. 1959
3 Sheets-Sheet 1
A104:2.,-
324% Imp/544E;
Sept. 4, 1962
o. DITTRICH ETAL
3,052,132
CONTROL MECHANISM FOR INFINITELY VARIABLE GEARS
Filed Dec. 10. 1959
3 Sheets-Sheet 2
5
25
L9
77
28 32
72 70
IN VEN TORJ'
Sept. 4, 1962
3,052,132
o. DlTTRlCH ETAL
CONTROL MECHANISM FOR INFINITELY VARIABLE GEARS
3 Sheets-Sheet 5
Filed Dec. 10. 1959
W5’! v "
17/775
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77
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BY
Awa [P669
A69
3 r
@YTOrIVP VJ
United States Patent 0
3,052,132
Patented Sept. 4, 1962
2
1
3,052,132
CONTROL MECHANISM FOR INFINITELY
VARIABLE GEARS
Otto Dittrich, Bad Hamburg vor der Hohe, Rudolf
Schrodt, Kronberg (Taunus), and Erhardt Karig, Bad
Homburg vor der Hohe, Germany, assignors to Rel
mers-Getriebe KG, Ascona, Switzerland, a ?rm of
Switzerland
Filed Dec. 10, 1959, Ser. No. 858,638
Claims priority, application Germany Dec. 12, 1958
5 Claims. (Cl. 74-23017)
The present invention relates to a control mechanism
for in?nitely variable gears, and more particularly to
improvements in a mechanism as described in the co
pending application, Serial No. 826,087, ?led on July 9,
1959, now Patent No. 2,993,385, and entitled “Control
Device for In?nitely Variable Gears.”
The mentioned application described a control mech
anism for in?nitely variable gears in which the drive shaft
rolling bodies will be disposed at the bottom of the cam
surfaces. If this slidable disk is then shifted in the axial
direction toward the ?xed pulley disk in order to change
the gear ratio, the associated cam surfaces on the conical
disk and on the cam bushing will be turned relative to
each other in the peripheral direction, whereupon the
rolling bodies will roll upwardly along the cam surfaces.
Since the cam surfaces have a changing pitch, this will
result in a change in the factor of proportionality of the
conversion of the torque into the axially directed pres
sure. In this manner it is possible to adapt the contact
pressures between the driving and driven parts to the
particular prevailing torque and to the particular pre
vailing gear ratio so that they will always be of an
amount as required for transmitting the power by fric
tional engagement with the best possible efficiency.
If, for example, in a gear of a motor vehicle, the
direction of the torque changes while the direction of
rotation remains the same, as when the engine no longer
and the driven shaft of the gear each carries a pulley 20 drives the vehicle through the gear, for instance, when
driving uphill, but the vehicle drives the motor through
which consists of two conical disks, at least one of which
the gear, as when driving downhill and using the engine
is slidable in the axial direction relative to the other
as a brake, the rolling bodies of the pressure-applying
disk, so as to act upon a belt or chain between them,
devices as above described, which transmit the power
and in which the driving side of the gear is subjected to
control forces which are dependent upon the load to 25 between the associated cam surfaces, must now engage
with the other cam surfaces of each pair which ascend
- which the gear is subjected and which are produced by
from the bottom in the inverse circumferential direction
the hydraulic pressure of a pressure ?uid so as to main
which results in relatively large idle traveling distances
tain and vary the gear ratio, while mechanical pressure
applying devices are provided for producing the axially
directed pressure which is required for transmitting the
necessary driving friction to the belt or chain which
connects the driving and driven parts of the gear, which
pressure is dependent upon the torque on the particular
gear shaft as well as upon the particular gear ratio to
which the gear is being adjusted.
of the rolling bodies depending upon the particular gear
ratio as adjusted, that is, the distances which the rolling
bodies have to travel during the free angular movement
of the shaft until they engage with the corresponding
points on the opposite cam surfaces.
In order to prevent
the rolling bodies at this operation from disengaging from
Each of these pres 35 the cam surfaces, the cam bushing is designed in a known
manner so as to be slidable in the axial direction along
sure-applying devices comprises at least one pair of heli
the gear shaft and to be acted upon by a compression
cal cam surfaces which have a changing pitch and ex
spring which presses the cam bushing toward the friction
tend inversely to each other in the peripheral direction
disk so that the rolling bodies will be held in engagement
in accordance with the two possible directions of the
40 with the cam surfaces and moved downwardly along
torque which may be acting on the particular shaft.
them to the cam bottom. If the' rolling elements then
Gears of this type are usually made in the form of
again move upwardly along the opposite shaped cam sur
cone-belt pulley drives in which two pulleys, each of
faces of the pair until they reach the new point of opera
which consists at least of a pair of conical disks, are
mounted on two parallel gear shafts and are connected 45 tion, the cam bushing will again be forced back by
the rolling bodies against the action of the compression
to each other by one or more endless belts or chains.
spring to its starting position, i.e. to the normal operating
Such gears may, however, also be provided with shafts
position in which it abuts in the axial direction against
which are disposed at an angle to each other, in which
a ?ange or the like on the gear shaft.
event the conical disks will either be in positive engage
ment with each other or be indirectly connected to each
other by means of suitable friction elements.
The principle of operation of the pressure-applying de
Although the spring force of the compression spring is
counteracting the back movement of the cam bushing and
thereby increasing its strength, it has been found that at
rapid torque changes, sudden impact stresses will occur
when the cam bushing hits against the ?xed ?ange on the
vices which are used in such gears is known as such and
consists of two or more pairs of helically ascending cam
surfaces on a cam bushing, which is nonrotatably se 55 shaft, while immediately prior thereto the required axial
pressure acting upon the slidable disk 1will not always be
available.
The principal objects of the present invention are to
overcome the above~mentioned disadvantages of the pres
conical disk of a pulley, which disk is nonrotatably 60 sure applying device of that type of gears in which the
control forces, which are required at the respective driv
mounted on the shaft and is slidable in the axial direc
ing side of the gear for maintaining and varying the gear
tion, whereby the torque action upon said shaft is trans
ratio, are produced hydraulically, and to attain a smooth,
mitted to the conical disk and at the same time an axially‘
shockless movement of the pressure-applying device when
directed pressure is produced which is proportional to the
torque acting on the gear shaft and is directed toward 65 a change in torque occurs and also to insure that the
available axial pressure will be of an adequate strength
the axially ?xed pulley disk. The factor of propor
cured to the shaft, and by means of rolling bodies such
as balls which are adapted to roll along these cam sur
faces and to act upon other cam surfaces of an identical
shape and number which are provided on the hub of a
tionality is determined by the particular angle of inclina
during this operation.
These objects are attained according to the invention
by providing a cam bushing which forms a part of the
ciated cam surfaces at the particular point thereon in
which they engage with the rolling bodies between them. 70 pressure-applying device and is mounted on the gear
shaft in the usual manner so as to be nonrotatable rela
If the slidable conical disk is shifted in the axial direction
tive thereto but slidable in the axial direction toward the
to the greatest distance from the ?xed pulley disk, the
tion or pitch of each of the two or more pairs of asso
’ 3,052,132
slidable conical disk under the action of a compression
spring, and which is supported in the opposite axial di
rection by a stop member, and by designing this bushing
adapted gradually to reduce the cross-sectional area of
?ow of the throttling apertures when the cam bushing is
being shifted against the action of the compression spring.
in the form of a damping piston which is mounted in a
cylinder and separates a damping chamber which rotates
with the gear shaft, from a likewise rotating pressure
chamber in which by means of the pressure ?uid the con
be attained by providing the damping piston with throttling
piston ring is slidable in the axial direction against spring
trol forces are produced which are dependent upon the
action so that, when the cam bushing is being shifted in
load and act upon the slidable cone pulley disk. These
the direction of the action of the compression spring, this
objects are further attained by the provision of throttle
valves in the damping piston which are active in one di
rection and are adapted at a change in the direction of the
torque during the displacement of the cam bushing in
the direction of force of the compression spring, to allow
Still another very suitable design of a throttle valve may
apertures and an annular recessed collar on which a
piston ring will lag relative to the movement of the piston
and thereby uncover a plurality of apertures which are
provided within the wall of the collar and terminate into
the damping chamber of the cylinder, while when the cam
bushing is being shifted in the opposite direction, this
the pressure ?uid free access from the pressure chamber 15 piston ring Will close these apertures.
into the damping cylinder, while during the subsequent
displacement of the cam bushing in the opposite direc
‘tion these valves force the pressure ?uid to ?ow back from
the damping cylinder into the pressure chamber by passing
through throttling apertures.
These inventive means insure that, at a change in
torque, the cam bushing will, under the action of the
compression spring, be shifted quickly and practically
The mechanism according to the present invention may
be applied to gears which are provided with such a pres
sure-applying device only on one shaft and also to those
which have such devices on both shafts. It is especially
of advantage in those gears in which the strength of the
control'force which is hydraulically produced in accord
ance with the load to which the gears are subjected de
pends upon the position of one of the slidable conical
without any resistance toward the slidable cone-pulley disk
disks. As soon as, due to an insu?icient pressure, the
and thereby take the rolling bodies along the cam path 25 slidable disk of these gears moves during the torque re
down to the cam bottom without, however, disengaging
versal in the direction toward the cam bushing, the con
from them during that time, whereas during the return
trol force will be immediately very strongly increased
movement of the cam bushing additionally to the spring
since, in such a control device where the control force is
force very strong hydraulic forces acting in the axial di
also controlled in accordance with the distance of travel '
rection will be created since the pressure ?uid can then 30 of the disk, a very small displacement of the disk will re?ow back from the damping cylinder to the pressure
sult in an extremely steep increase in pressure within the
chamber only through the throttling apertures. During
pressure chamber which will insure that the conical disk
this part of the operation, the damping action very
will remain substantially in the position to which it has
strongly increases the strength of the contact pressure
once been adjusted.
which should be produced by the pressure-applying mech 35 The control forces which may be produced at the driv
anism but cannot be supplied because the rolling bodies
ing side as well as the driven side of such gears as are
are traveling from one engagement point on one of the
cam surfaces to the corresponding engagement point on the
opposite cam surfaces of each pair of cam surfaces,
which traveling is due to the reversal of the torque.
Also at the end of its movement the cam bushing will en
gage practically without any impact with the ?ange on the
gear shaft.
described in ‘detail in the mentioned copending appli
cation therefore contribute during a torque reversal to
the effect of the damping device according to the present
invention in supplying an additional ?uid pressure dur
ing the movements of the cam bushings on both shafts
whenever a higher pressure against the slidable pulley
disk is required.
The effect of this damping mechanism upon the cam
These and other objects, features, and advantages of
bushing will be further increased due to the fact that 45 the present invention will become further apparent from
the control forces which are produced hydraulically
the following detailed description thereof, particularly
within the pressure chamber are of a strength in propor~
when the same is read with reference to the accompany
tion to the torque acting upon the gear shafts at any par
ing drawings, in which
ticular time. Consequently, these control forces increase
FIGURE 1 shows partly diagrammatically a longi
to the same extent at which the oppositely directed torque
tudinal cross section of the two shafts of an in?nitely.
is being built up, and they also contribute to the result that
the axial pressure acting upon the slidable cone-pulley
disk will never be of a strength less than required, al
though the rolling bodies will be out of normal operation
variable gear with conical pulley disks, and of the control
during that period.
A perferred embodiment of the present invention com
prises a damping cylinder which is open at one side and
connected to the gear shaft so as not to- be displaceable
in'the axial direction thereof and which also serves as
mechanism according to the invention;
>
FIGURE 2 shows a cross section similar to FIGURE 1
of one set of cone-pulley disks and the associated control
55 mechanism according to a modi?cation of the invention;
FIGURES 3 and 4 show partial cross sections of the
throttle valve as used in the embodiment according to
FIGURES '1 and 2 in two different operating positions;
FIGURE 5 shows a view similar to FIGURE 2 with a
the ?xed part of the pressure chamber for producing the 60 control mechanism according to a further modi?cation
hydraulic control forces, while the movable part of this
of the invention.
chamber is formed by the axially slidable cone-pulley
FIGURES 6 and 7 shows partial cross sections of the
disk having a cylindrical ?ange which is slidably mounted > throttle valve as used in the embodiment according to
within or on the damping cylinder.
FIGURE 5 in two different operating positions;
The one-way throttle valves which are mounted in the 65 ' FIGURE 8 shows a cross section of a mechanism sim
damping piston may be of various types of construction.
ilar to FIGURES 2 and 5, but with a throttle valve ac
Thus, for example, they may consist of a plurality of rela
tively large apertures which are closed at the side of the
damping chamber of the cylinder by means of a spring
loaded annular valve plate, and of throttling apertures
cording to a third modi?cation;
FIGURES 9 and 10 show partial cross sections of the
throttle valve according to FIGURE 8 in two different
of a small cross section Within the damping piston or the.
FIGURE 11 shows a partial cross section of a different
operating positions; while
valve plate. According to another embodiment of the in
type of gear with crossing shafts.
vention, tapering throttling pins which are rigidly se
Referring to the_drawings,,FIGURE 1 shows an in
cured to the damping cylinder extend into the throttling
?nitely variable cone-pulley gear which is driven by a
apertures in the damping piston or valve plate and are 75 belt or link chain and comprises two parallel shafts I
3,052,132
5
and 2, each of which carries a pair of conical pulley disks
3, 4 and 5, 6, respectively. The conical disks 3 and 5
are mounted on their respective shafts 1 and 2 so as to
be rotatable as well as slidable thereon in the axial direc
tion, while the conical disks 4 and 6 are connected to
disks 3 or 5, respectively, so as to be nonrotatable but
slidable in the axial direction relative thereto, and these
disks 4 and 6 are supported against a movement in the
axial direction relative to shafts 1 and 2 by ball bearings
6
motor, while shaft 2 is connected to the machine which
is to be driven. Since belt 53 as illustrated in FIGURE 1
runs on the driven side of the gear at the smallest possible
radius of pulley 5, 6, shaft 2 will be driven at the highest
rate of speed. Since pulley disks 5 and 6 are spaced from
each other at the greatest possible distance, balls 14
will lie at the bottom of cam surfaces 12 and 16. ‘On
the driving side of the gear, that is, on shaft 1, pulley
disks 3 and 4 are moved to the smallest possible distance
7 and 8, respectively. The two pulleys formed by the 10 toward each other and, due to the fact that cam bushing
two pairs of conical disks 3, 4 and 5, 6 are connected to
each other by an endless belt or chain 53, hereafter re
ferred to as a “belt.” On the faces of their hubs 9 and
10, each disk 3 and 5 is provided with cam surfaces 11
or 12, respectively which are operatively associated by
17 is assumed to be shifted to the right in the axial direc
tion, balls 13 are likewise disposed at the bottom of cam
surfaces 11 and 15. If shaft 1 is then rotated, it also
rotates cam bushing 17, whereas the conical pulley disks
3 and 4 will at ?rst remain at a standstill. Balls 13 will
then run upwardly along the opposite cam surfaces 11
and 15 and thereby force cam bushing 17 back in the
corresponding cam surfaces 15 or 16 on the face of a
axial
direction to the left until its end surface 21 engages
bushing 17 or 18, respectively. These cam bushings 17
with end stop 23. Since there is thus no further pos
and 18 are mounted on shaft 1 or 2, respectively, and are
slidable thereon against the action of a compression 20 sibility of movement of cam bushing 17, the torque act
ing on shaft 1 will be transmitted from cam bushing 17
spring 19 or 20. When cam bushings 1'7 and 18 are in
through balls 13 to pulley disks 3 and 4, while at the
their normal position their outer end surfaces 21 and 22
same time a pressure will be exerted in the axial direc
will be in engagement with end stops 23 and 24 to pre
tion upon the conical disk 3 which is of a strength in
vent the bushings from sliding ‘further in the axial direc
tion. This is illustrated particularly by bushing 18, while O proportion to that of the torque on shaft 1 and is also
dependent upon the particular gear ratio to which the
the other bushings 17 is shown in the position in which
gear has been adjusted, due to the fact that the inclina
it is disposed at the time of the torque reversal when it
tion
of said cam surfaces is not constant and that the
is shifted by the compression spring 19 against the conical
balls 13 will have run upwardly along said cam surfaces
disk 3 and has moved balls 13 to the lowest point on cam
30 to an extent which is de?ned by the position of slidable
surfaces 11 and 15.
disk 3, the position of which in turn de?nes the gear ratio.
At the side facing toward the slidable pulley disk 3
Due to this pressure, belt 53 will be clamped between
or 5, respectively, each shaft 1 and 2 carries a damping
the slidable pulley disk 3 and. the axially ?xed pulley disk
cylinder 25 or 26 in the form of a cup-shaped member
means of rolling bodies in the ‘form of balls 13 or 14 with
4 with such a force that the full driving power of belt
53 will be transmitted to pulley 3, 4. At the same time,
balls 14 on the driven side of the gear will also tend to
ings 17 and 18 form damping pistons 27 and 28 which
run upwardly along cam surfaces 12 and 16 under the
separate the damping chamber 29 or 30 in cylinder 25
effect of the torque of the driven shaft, but will ‘be able
or 26 from a pressure chamber 31 or 32, respectively,
to do so only by changing the radius of engagement of
which is formed at one side by the peripheral wall of
cylinder 25 or 26 and at the other side by the slidable 40 belt 53 with pulley disks 5 and 6. The torque on shaft 2
is then transmitted from this shaft through cam bush
pulley disk 3 or 5 and a ?ange 33 or 34 thereon.
ing
18 and balls 14 to the slidable pulley disk 5, while
These pressure chambers 31 and 32 contain a pressure
at the same time a pressure force is produced which is
?uid which is supplied thereto from a container 37 by a
of a size in proportion to the torque on shaft 2 and also
gear pump 38 through a pressure-relief valve 39, a con
trol cylinder 40, the diagrammatically indicated pressure 45 dependent upon the particular gear ratio as set, that is,
dependent upon the inclination of that part of the cam
lines 35 and 36, and suitable bores in shafts 1 and 2.
which rests against a ?ange on the respective shaft and
also forms the end stop 23 or 24, respectively. Cam bush
Control cylinder 40 contains two control pistons 41 and
42. When these pistons are in a central position in cylin
der 40, they permit the pressure ?uid to ?ow into pressure
lines 35 and 36 and also to pass around control pistons
41 and 42 and then to ?ow back from chambers 43 and
44 through return lines 45 and 46 and an adjustable
throttle valve 47 to container 37. If control pistons 41
and 42 are shifted only slightly in one direction, for ex
ample, toward the left, the flow of pressure ?uid to line
36 will be throttled, while at the same time line 36 will
be connected with return line 46. The pressure of the
pressure ?uid in chamber 32 is therefore primarily deter
mined by the particular adjustment of throttle valve 47 .
At the same time, however, the pressure ?uid will be
allowed to pass more freely into pressure line 35, while
its ?ow into cylinder chamber 43 will be throttled. A
pressure will thus be built up in pressure chamber 31 of
the pulley on shaft 1 which is dependent upon the amount
of axial displacement of control pistons 41 and 42 in con
trol cylinder 40. Piston rod 48 of control pistons 41 and
surfaces (here the bottom) against which the balls 14 bear.
Assuming that pressure chamber 31 on shaft 1 does
not contain any pressure, the gear ratio of the gear would
50 be changed since the spreading force exerted by belt 53
upon the conical pulley disks 3 and 4 is always greater
than the axial pressure produced by cam bushing 17 and
exerted upon disk 3.
This would result in a reduction of
the radius of engagement of belt 53 with the driving pulley
55 disks 3 and 4 and a corresponding increase of the radius
of engagement of belt 53 with the driven pulley disks 5
and 6 since the slidable disks 3 and 5 would both yield
toward the left, as seen in FIGURE 1. The consequence
of the movement of slidable disk 5 to the left would be
60 that the control pistons 41, 42 would be shifted through
the two-armed lever 49 toward the left, whereby, as
more fully described in the co-pending application Serial
No. 826,087, ?led on July 9, 1959, now Patent No.
2,993,385 and entitled “Control Device of In?nitely Vari
65 able Gears,” even at the slightest movement of these
pistons a control pressure would be built up in pressure
chamber 31 on drive shaft 1 which would be sufficient
to prevent any noticeable further change in the gear ratio.
At the same time, the pressure would decrease in pressure
chamber 32 to such an extent that only the minimum pres
lever which may be adjusted either by hand or by other
sure would prevail which is determined by throttle
means, not shown, for example, a threaded spindle, a
valve 47.
servo-control mechanism or the like.
If the torque on the driven shaft 2 is increased, the
Insofar as it has been described above, the gear accord—
slidable pulley disk 5 will likewise tend to escape toward
ing to FIGURE 1 operates as follows: Let us assume
that shaft 1 is the shaft which is connected to the driving 75 the left with the result, as already mentioned above, that
42 is connected to a two-armed lever 49, one end 56 of
which engages into an annular groove 51 on the slidable
pulley disk 5, while its other end 52. serves as a control
3,052,132
7
the pressure in pressure chamber 31 on drive shaft 1 will
force will be exerted in the axial direction upon the coni
cal pulley disk 3 or 5, so that the required pressure against
belt 53 will be maintained. Furthermore, at the end
immediately increase accordingly so that the gear ratio as set will remain unchanged.
If the gear ratio should be changed, lever ‘49 must
be shifted at its end 52 toward the right, whereby con
trol pistons 41 and 42 will also be shifted toward the
right with the result that the pressure in pressure chamber
of the return movement of cam ‘bushing 17 or 18, its end
surface 21 or 22 will engage gradually and practically
without impact with the stop surface 23 or 24, respec—
tivel .
31 will decrease and the slidable pulley disks 3 and 5
Inythe event that this return movement of, for example,
cam bushing 17 on the ‘driving side ‘of the gear is re
change in the radii of engagement of belt 53, while at the 10 tarded to such an extent that the pressure of the bushing
same time the control pistons 41 and 42 will again return
will not be suf?cient and the slidable pulley disk 3 and 5
to the starting position so that a state of equilibrium
will have the tendency to yield toward the left, control
will again be produced between the spreading force gen
pistons 41 and 42 will also move toward the left with the
erated by belt 53 011 the driving side and the pressure
result that a steep rise in pressure will be immediately pro
will be shifted toward» the left.
This will result in a
against the belt which counteracts these spreading forces 15 duced in pressure chamber 31 whereby the effect of damp
and is produced by cam bushing 17 and the control force
ing piston 27 or 28 of cam bushing 17 or 18 will be am;
generated by the pressure medium in pressure chamber
pli?ed. The same procedure equally applies to the cor
31. When the gear ratio is thus being changed, balls 13
responding parts on the driven side of the gear.
on the driving side will move along cam surfaces 11
The mechanism according to the present invention
and 15 slightly inwardly toward the cam bottom, while
therefore insures a smooth, shockless movement of the
balls 14 on the driven side will move a small distance
cam bushings when the torque is being reversed, and at
away from the cam bottom and upwardly along cam
surfaces 12 and 16.
Assuming that the direction of the torque on the driven
shaft 2 is suddenly reversed, this shaft and cam bushing
18 will carry out a rotation relative to pulley disks 5
and 6. Balls 14 will then run back into the cam bottom,
while the cam bushing 18 will be shifted toward the left
the same time also the generation of a sufficient pressure
against belt 53.
FIGURE 2 illustrates a modi?cation of the pulley struc
; ture on shaft 2.
While in the embodiment according to
FIGURE 1, ?ange 34 on the slidable pulley disk 5 over
laps the damping cylinder 26 on the outside thereof, the
cylindrical ?ange 65 according to FIGURE 2 extends into
by the force of spring 20 and thereby maintain balls 14
damping cylinder 26.
in engagement with cam surfaces 12 and 16.
FIGURES 3 and 4 have already been described with
reference to the embodiment according to FIGURE 1 and
Since the 30
direction of the torque is then also reversed at the driving
side of the gear, a relative rotation also occurs between
shaft 1 with cam bushing 17 and pulley disks 3 and 4,
illustrate the manner of operation of throttle valve 57 or
58 on damping piston 27 or 28 of cam bushings 17 or 18,
so that balls 13 will likewise run down toward the cam
respectively.
bottom, While being held in engagement with cam sur
FIGURES 5 to 7 and 8 to 10, respectively, illustrate
two further modi?cations of the 1one-way throttle valve
faces 11 and 15 by the action of compression spring 19
which shifts cam bushing 17 toward the right. In the
subsequent course of the operation, balls 13 and 14 will
run on both the driven and driving sides of the gear
upwardly along the inversely directed cam surfaces 11,
15 and 12, 16 and thereby again force cam bushings
17 and 18 backwardly until their end surfaces 21 and 22
engage with stop surfaces 23 and 24.
The axial displacements of cam bushings 17 and 18
occurring at a torque reversal as just described are con
trolled, on the one hand, by compression springs 19 and
20 and, on the other hand, by a damping mechanism as
subsequently described.
As already mentioned above, each cam bushing 17 and
‘and their manner of operation. FIGURES 5 and 8 are
similar to the upper half of the gear on shaft 1 in FIG
URE 1, while FIGURES 6 and 7, and 9 and 10 are similar
to FIGURES 3 and 4, respectively. Cam bushing 17 of
the embodiment according to FIGURES 5 to 7 forms a
damping piston 70‘ which is provided with an annular
recessed collar on which a piston ring 72 is mounted so
as to be slidable in the axial direction against the action
'H ‘of a spring.
When cam bushing 17 is being shifted in the
direction of force of compression spring 19, piston ring
72 will lag relative to piston 70, as shown particularly in
FIGURE 7, and thereby free the apertures 73 which
extend radially through the wall of collar 71 into damp
18 is designed in the form of a damping piston 27 or 28 50 ing chamber 29. When cam bushing 17 moves in the
which separates the ‘damping chamber 29 or 30 of cylin
opposite direction, these apertures '73 will again be imme
der 25 or 26 from the pressure chamber 31 or 32, respec
tively. Each damping piston 27 and 28 is provided with
a plurality of peripherally spaced apertures 55 and 56
diately closed by piston ring 72. Damping piston 70 is
further provided with throttling apertures 74 through
which the pressure ?uid must ?ow during the return
of a relatively large cross section which are closed at 55 movement of the cam bushing. The principle of opera
tion of this lag valve is the same as that of the plate valve
the side facing toward damping chamber 29 or 30 by an
annular spring-loaded valve plate 57 or 58. Each damp
ing piston 27 or 28 is further provided with a plurality of
throttling apertures 59 or 60 of a relatively small cross
section. As illustrated in detail in FIGURES 3 and 4,
valve plate 57 or ‘58 will be lifted from piston 27 or 28
when the respective cam bushing is being shifted under the
;action of compression spring 19' or 20 in the direction
toward the slidable pulley disk 3 or 5. The pressure ?uid
can then pass freely from pressure chamber 31 or 32
through apertures 55 or 56 into damping chamber 29‘ or
30, respectively. At the beginning of the return movement
of cam bushing 17 or 18 against the action of compres
sion spring 19 or 20, valve plate 57 or 58 will again close
apertures ‘55 or 56 whereby the movement of the cam
bushing will be strongly retarded due to the opposing
force of spring 19 or 20 and to the fact that the pressure
?uid can now ?ow back from damping chamber 29 or 30
to pressure chamber 31 or 32 only by passing through the
throttling apertures 59 or 60. Consequently, a strong
as described with reference to FIGURES 1, 3, and 4.
The damping piston on cam bushing 17 according to
FIGURES 8 to 10 is again provided with a plurality of
apertures 55 similar to those in FIGURE 1, which are
covered by a spring-loaded valve plate 75. This valve
plate is, in turn, provided with throttling apertures 76,
into which throttling pins 77 extend which are mounted
on the end wall of damping cylinder 25 and taper to a
point at the front ends which are adapted to enter into
apertures 76. When cam bushing 17 moves back in the
direction toward the end stop 23, the throttling apertures.
have at ?rst a relatively large cross section, but the closer,
the bushing moves toward stop 23, the more these aper
tures 76 will be closed by throttling pins 77. The damp-.
ing action therefore increases gradually.
FIGURE 11 ?nally illustrates that the invention is not
limited to pulley gears with slidable conical disks, but that
it may also be applied to other types of in?nitely variable
75 gears. In this particular example, the gear concerned is
3,052,132
a friction gear in which the drive shaft 100 and the driven
shaft 103 are disposed at right angles to each other. The
driving part of the gear on drive shaft 1%‘ is of the same
construction as the left part of the drive-pulley unit on
10
cross section in said piston, and one-way valve means
on said piston for opening and closing said large aperture
and adapted to open to permit the pressure ?uid to pass
freely from said pressure chamber to said damping cham
ber when, after the torque on said shaft has changed its
direction and said rolling bodies have to travel from the
particular point on one of the cam surfaces of each pair to
the corresponding point on the other cam surface forming
shaft 1 according to FIGURE 1, while the driven part of
the gear is here designed in the ‘form of a conical friction
disk 101 which is in direct friction-engagement with
the conical driving disk 102. The change in gear ratio is
a pair with the ?rst-mentioned cam surface, said cam
produced in a known manner by shifting the driven disk
bushing and piston are ?rst shifted in the direction to
101 in the axial direction along its shaft ‘103 by means of 10 ward said slidable disk by the force of said spring, said
a threaded spindle, whereby driving disk v119?, will also be
valve means being further adapted to close said large aper
shifted along its shaft 109. The principle of operation of
ture when said bushing and piston then move back to the
damping the movement of the cam bushing during the
normal position in the opposite direction and then to
torque reversal is substantially the same as that previously
force said pressure ?uid to return under a high pressure
15
described with reference to FIGURES l and 10.
from said damping chamber to said pressure chamber by
Although our invention has been illustrated and de
passing through said throttling aperture.
scribed With reference to the preferred embodiments there
2. A ‘gear mechanism as de?ned in claim 1, further com
of, we wish to have it understood that it is in no way lim
prising a ?xed conical disk mounted on each of said shafts
ited to the details of such embodiments, but is capable of
and rigidly connected thereto, said slidable disk being op
numerous modi?cations within the scope of the appended 20 eratively associated with and slidable relative to said ?xed
claims.
disk, said slidable and ?xed disks on each shaft together
Having thus fully disclosed our invention, what we
forming a cone pulley, said connecting means forming an
claim is:
endless beltlike member connecting the two pulleys, all of
1. In an in?nitely variable gear mechanism having a
said load-responsive means forming separate means op
25
driving shaft and a driven shaft, at least one conical disk
eratively connected to said slidable disk on each of said
on each shaft and slidable along and rotatable on said
shafts.
shaft, means connecting said disks to transmit a driving
3. A gear mechanism as de?ned in claim 1, in which
force from one shaft to the other, and load-responsive
said damping piston is provided with a plurality of said
means operatively connected to at least said conical disk
‘large apertures and a plurality of small throttling aper
on said driving shaft to force said disk toward said con
tures, said valve means comprising an annular spring
necting means and to maintain said disk substantially in
loaded valve plate adapted to open and close all of said
a preset position even if the load changes, said load
large apertures.
:responsive means comprising a cylinder rigidly secured to
4. A gear mechanism as de?ned in claim 1, in which
at least said driving shaft, a second cylinder axially slid
said damping piston is provided with a plurality of said
35
able and rotatable with said disk on said driving shaft,
large apertures, said valve means comprising an annular
each of said two cylinders having one open end, said cylin
spring-loaded valve plate adapted to open and close all of
ders being telescopically slidable at said open ends one
said large apertures, said valve plate having a plurality
within the other and relative to each other, a source of
of
said small throttling apertures therein, and tapering
?uid under pressure, a line connecting said source to one
40 throttling pins rigidly secured to said damping cylinder
‘of said cylinders, means operatively associated with said
and extending into said throttling apertures and adapted
line and operatively connected to one of said slidable
gradually to reduce the cross sectional passage of said
disks and controlled thereby to regulate the ?uid pressure
apertures when said cam bushing and piston are shifted in
in said cylinders for automatically maintaining a predeter
the direction opposite to the direction of force of said
mined transmission ratio between said shafts, deliberately 45 compression spring.
adjustable means operatively connected to said regulating
5. A gear mechanism as de?ned in claim 1, in which
means for varying the transmission ratio, a bushing on said
said damping piston has an annular recessed collar thereon
driving shaft and slidable along and rotatable with said
and said larger apertures being therein and terminating
shaft within said cylinders, a damping piston rigid with
into said damping chambers, a piston ring slidably mount
said bushing and slidable therewith within said cylinders 50 ed Within the recessed part of said collar and adapted to
and forming therein a pressure chamber and a damping
open and close said apertures in said collar, a spring acting
chamber at opposite sides of said piston, said line connect
upon said piston ring and in the same direction as said
ing said source to said pressure chamber, a plurality of
helical cam surfaces of a changing pitch arranged in pairs
on the opposite faces of said slidable disk and said bush
ing, the two cam surfaces of each pair being arranged in
versely to each other in the circumferential direction in
accordance with the two possible directions of the torque
acting on said shaft, rollable bodies between said cam sur
faces and in engagement with a particular point of one of
said cam surfaces of each pair on the opposite faces of
said slidable disk and said bushing, respectively, a com
pression spring acting upon said bushing and piston tend
ing to move the same in the direction toward said slidable
disk and maintaining said cam surfaces at all times in en
gagement with said rolling bodies, a stop member limiting
the sliding movement of said bushing and piston in the
opposite direction, at least one throttling aperture of small
cross section in said piston, at least one aperture of large
‘compression spring, said piston ring being adapted to lag
relative to said piston when said bushing and piston are
being shifted in the direction toward said slidable disk by
the force of said compression spring so as then to uncover
said apertures in said collar, said piston ring being adapted
to close said apertures in said collar when said cam bush
ing and piston are shifted in the opposite direction.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,233,967
Wellton _____________ __ Mar. 4, 1941
2,346,868
2,651,208
Perry ________________ __ Apr. 18, 1944
Karig _______________ __ Sept. 8, 1953
2,779,203
2,810,296
Eubanks _____________ __ Jan. 29, 1957
Long _______________ __ Oct. 22, 1957
2,887,893
Olaas _______________ __ May 26, 1959
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